Digital recording/reproducing apparatus

ABSTRACT

Based on a digital recorder/player taken as a basic apparatus and which accommodates a field frequency of 60 fields/sec or a frame frequency of 30 frames/sec, an apparatus is implemented to record or reproduce source video and audio signal originated from the basic apparatus and whose frequency is different from the field or frame frequency. The apparatus includes an input unit, a processor, and a converter provided between the input unit and the processor. The input unit accepts audio data having a specific field frequency and arranged in a specific format, and make baseband processing of the audio data. The processor is designed to process audio data having a basic field frequency (60 fields/sec) and arranged in a basic format. It operates with a clock corresponding to the sampling frequency to make error-corrective encoding of the audio data adapted to the basic format.

TECHNICAL FIELD

The present invention generally relates to a digital audio recordingmethod and apparatus, a digital audio playing method and apparatus, adigital video recording method and apparatus, a digital video playingmethod and apparatus and a digital video recording method and apparatus,and more particularly to implementing, based on a recording/playingapparatus taken as a basic apparatus and which accommodates audio orvideo data of a field frequency, a recording/playing apparatus whichaccommodates audio or video data different in field frequency from theaudio or video data accommodated by the basic apparatus. Morespecifically, the present invention is directed to simplification of arecording/playing apparatus, for example, audio and video sections of aVTR. However, it should be noted that the present invention is notlimited to any VTR.

BACKGROUND ART

The recording/playing apparatus such as a VTR will be very convenient ifit can record or reproduce signals defined according to a plurality ofdifferent television standards. More particularly, the VTR shoulddesirably be capable of recording or reproducing signals used in thetelevision systems (TV system) adopted in all countries, respectively,over the world such as Japan, USA and Europe. The HDTV (high-definitiontelevision) system was first developed in Japan to display ahigher-definition picture than the conventional TV system. In Japan, theHDTV system is called “Hi-Vision” system and defined as using 1125scanning lines and a field frequency of 60 Hz. On the other hand, theHDTV systems in the Europe and USA are different in various aspects fromthe Hi-Vision system in Japan. For example, the field frequency in theEuropean HDTV system is 50 Hz.

The TV system varies among the countries as above, and hence TVequipment and materials used in a country for program production andbroadcasting are thus inevitably different from those used in anothercountry. Namely, the TV equipment and materials for production andbroadcasting have to developed and manufactured for conformity with thedifferent TV systems, respectively, which will lead to large costs ofprogram production and broadcasting. Also, for playing a softwareproduced in compliance with a TV system, a VTR conforming to that TVsystem has to be used and TV signals have to be converted in format by aseparate format converter for re-recording to the VTR, which will alsolead to increased labor and cost.

The VTR is one of the essential equipment and materials for producingand broadcasting a program. Generally, since the broadcasting VTRs areat heavy prices, so it is desired that a tape transport, signalprocessing circuit, tape cassette and the like are usable in commonbetween VTRs conforming to different HDTV systems. This will lead to areduction of the equipment costs and running costs and also be veryprofitable to the users. Also, if a tape having a program recordedtherein in compliance with a plurality of different TV systems can beplayed in the same VTR, the program can advantageously be exchangedamong the countries adopting the different TV systems, respectively, atlow costs.

However, the conventional magnetic recording/playing apparatuses like aVTR do not incorporate any recording/playing mechanism common to suchdifferent HDTV systems and thus cannot record and reproduce anyhigh-definition video data and audio data produced in compliance withthe HDTV systems. For an apparatus capable of recording and reproducingsignals different in field frequency from each other, a processor wasrequired which formats each of the signals of different fieldfrequencies for the signals to be dealt with in the apparatus. Assumehere for example that there are two apparatuses one of whichaccommodates signals having a field frequency of 60 fields/sec, audioinput/output sampling frequency of 48 kHz and a number of bits persample of 24 and the other accommodates signals of 50 fields/sec infield frequency, 48 kHz in audio input/output sampling frequency and of24 in number of bits per sample. It should be noted that the apparatusfor data of 60 fields/sec in field frequency will also be referred to as“60-fields/sec apparatus or VTR” hereunder and the apparatus for data of50 fields in field frequency will also be referred to as “50-fields/secapparatus or VTR” hereunder. In this case, the audio format for the60-kHz apparatus should be 800 samples/field×24 bits/sample, and thatfor the 50-kHz apparatus be 960 samples/field×24 bits/sample. Betweenthese signals, there is a large difference in total number of bits perfield. Namely, the total number of bits per field of the signal havingthe field frequency of 60 fields/sec is 800×24(=19200) while that of thesignal of 50 fields/sec is 960×24(=23040). Therefore, the apparatusesfor recording and reproducing signals of different field frequencies areinevitably quite different in format from each other.

Also, the video frame varies between field frequencies. Therefore, anapparatus for a signal of one field frequency was unavoidably quitedifferent in signal format from an apparatus for a signal of anotherfield frequency.

DISCLOSURE OF THE INVENTION

Accordingly, the present invention has an object to overcome theabove-mentioned drawbacks of the related art by implementing, based on adigital audio recording/playing apparatus taken as a basic apparatus andwhich accommodates a field frequency, a digital audiorecording/reproducing apparatus which can accommodate audio data of afield frequency different from that for the basic apparatus byconverting the audio data into a format suitable for the basic apparatusand which can be processed at an appropriate rate.

Also the present invention has another object to implement, based on adigital video recording/playing apparatus taken as a basic apparatus andwhich accommodates a field frequency, a digital video recording/playingapparatus which can recording or reproducing video data different infield frequency from that accommodated by the basic apparatus byconverting the video data into a format suitable for the basic apparatusand which can be processed at an appropriate rate.

To overcome the above-mentioned drawbacks of the related art and attainthe above object, the present invention provides a digital audiorecording apparatus constructed as will be described below. Namely, thedigital audio recording apparatus includes, according to the presentinvention, an input unit for accepting audio data having a predeterminedsampling frequency and specific field frequency and a specific format inwhich specific data array and bit array are defined in units of a field,and making at least baseband processing of the audio data, a processordesigned to process the audio data having the predetermined samplingfrequency and a basic field frequency and a basic format in which thebasic data array and bit array are defined in units of a field, andoperate with a clock corresponding to the sampling frequency to makeerror-corrective encoding of the audio data adapted to the basic format,an output unit for writing the audio data output from the processor to arecording medium, and a converter provided between the input andprocessor. When the specific field frequency of the audio data isdifferent from the basic one and the specific format is different fromthe basic one, the converter converts the sampling frequency at a ratiobetween the specific field frequency and basic one while adapting thespecific format to the basic one, before passing the audio data thusprocessed to the processor which will operate with a clock correspondingto the converted sampling frequency to make error-corrective encoding ofthe audio data adapted to the basic format.

Specifically, the converter adapts the specific format to the basic oneby changing the number of samples per field and number of bits persample in combination while maintaining the total number of bits perfield which depends upon the product of the number of samples per fieldand number of bits per sample, and converts the sampling frequency bychanging the number of samples per field. Further, in case the totalnumber of bits per field which depends upon the product of the number ofsamples per field and number of bits per sample varies between thespecific format an the basic one, the converter corrects the number ofsamples per field by converting the sampling frequency of the inputaudio data, and adjusts the corrected total number of bits per field tothe total number of bits per field which depends upon the product of thecorrected number of samples per field and number of bits per sample.Alternatively, when the total number of bits per field which dependsupon the product of the number of samples per field and number of bitsper sample varies between the specific format and basic one, theconverter may correct the total number of bits by adding dummy datacorresponding to the deficit bits to the specific format and adjust thetotal number of specific-formatted bits to that of basic-formatted bits.Preferably, the converter should adapt the specific format to the basicone by writing audio data consisting of a bit stream of seriallyarranged samples to FIFO in units of a number of specific-formattedbits, reading the audio data in units of a number of basic-formattedbits, and changing the number of samples per field and number of bitsper samples in combination. In this case, the converter will adapt thespecific format to the basic one by controlling the write and read ofthe audio data to and from the FIFO synchronously with the specificfield frequency.

According to a variant of the above digital audio recording/playingapparatus, the processor incorporates the converter as a conversionmeans and further includes a coding means for making error-correctiveencoding of audio data. When the specific field frequency of the audiodata is different from the basic field frequency and the specific formatis different from the basic one, the conversion means adapts thespecific format to the basic one before passing the audio data to thecoding means, and the coding means operates with a clock correspondingto the predetermined sampling frequency to make error-correctiveencoding of the audio data adapted to the basic format with a pausetaken as needed at a rate corresponding to the ratio between thespecific field frequency and basic one. More specifically, theconversion means converts the specific format to the basic one bychanging the number of samples per field and number of bits per samplein combination while maintaining the total number of bits per fieldwhich depends upon the product of the number of samples per field andnumber of bits per sample. Further specifically, the conversion meansincludes as many registers as bits per basic-formatted sample, andconverts the specific format into the basic one by cyclically writingaudio data having a specific format consisting of a bit stream ofserially arranged samples to the registers while cyclically reading theaudio data from the registers with a pause taken as needed at a ratecorresponding to the ratio between the number of bits perspecific-formatted sample and number of bits per basic-formatted sampleand thus changing the number of samples per field and number of bits persample in combination.

Also the above object can be attained by providing a digital audioplaying apparatus including, according to the present invention, aninput unit for reading, from a recording medium, audio data having asampling frequency and specific field frequency and adapted to a basicformat in which a basic data array and bit array are defined in units ofa field, a processor designed to process audio data having apredetermined sampling frequency and basic field frequency and arrangedin the basic format, and operate with a clock corresponding to thesampling frequency to decode the audio data adapted to the basic formatfor at least error correction of the audio data, an output unit formaking at least baseband processing of the audio data output from theprocessor and supplying the audio data to a playback device, and aconverter provided between the processor and output unit. The processorcan operate with the clock corresponding to the sampling frequency ofthe read audio data to make error-corrective decoding of the audio dataadapted to the basic format. When the specific field frequency of theread audio data is different from the basic one and the specific formatis different from the basic one, the converter restores the audio dataonce adapted to the basic format to the specific format, converts thesampling frequency of the read audio data into the predetermined one ata ratio between the specific field frequency and basic one beforepassing the audio data to the output unit.

Specifically, the converter restores the audio data from the basicformat to the specific one by changing the number of samples per fieldand number of bits per sample in combination while maintaining the totalnumber of bits per field which depends upon the product of the number ofsamples per field and number of bits per sample, and converts thesampling frequency by changing the number of samples per field. Itshould be noted that when the total number of bits per field whichdepends upon the product of the number of samples per field and numberof bits per sample varies between the specific format and the basic one,the converter corrects the number of samples per field by converting thesampling frequency of the audio data once restored from the basic formatapproximately to the specific one, and finally converts the audio datainto the specific format. Alternatively, when the total number of bitsper field which depends upon the product of the number of samples perfield and number of bits per sample varies from the specific format tothe basic one, the converter may restore the audio data approximately tothe specific format by adding excess dummy data to the audio data onceadapted to the basic format, and then finally convert the audio datainto the specific format by removing the dummy data from the audio data.Preferably, the converter should restore the basic format to thespecific one by writing audio data consisting of a bit stream ofserially arranged samples to FIFO in units of the number ofbasic-formatted bits, reading the audio data in units of the number ofspecific-formatted bits, and changing the number of samples per fieldand number of bits per samples in combination. In this case, theconverter will restore the basic format to the specific one bycontrolling the write and read of the audio data to and from the FIFOsynchronously with the specific field frequency.

According to a variant of the above digital audio playing apparatus, theprocessor incorporates the converter as a conversion means and furtherincludes a decoding means for making error-corrective decoding of audiodata. The decoding means operates with a clock corresponding to thepredetermined sampling frequency, and makes error-corrective decodingaudio data adapted to the basic format with a pause taken as needed at arate corresponding to the ratio between the specific field frequency andbasic one. When the specific field frequency of the read audio data isdifferent from the basic field frequency and the specific format isdifferent from the basic one, the conversion means restores the audiodata once adapted to the basic format to the specific one before passingthe audio data to the output unit. Specifically, the conversion meansrestores the basic format to the specific one by changing the number ofsamples per field and number of bits per sample in combination whilemaintaining the total number of bits per field which depends upon theproduct of the number of samples per field and number of bits persample. More specifically, the conversion means includes as manyregisters as bits per basic-formatted sample, and restores the basicformat to the specific format by cyclically writing basic-formattedaudio data to the registers with a pause taken as needed at a ratecorresponding to the ratio between the number of bits perbasic-formatted sample and number of bits per specific-formatted sampleand cyclically reading the audio data from the registers whiledelimiting the audio data with the number of bits per specific-formattedsample, and changing the number of bits per field and number of bits persample in combination. It should-be noted that for forward play orreverse play of audio data, whichever should selectively be done inwriting or reading the audio data to or from the registers, theconversion means starts with MSB of a bit string for the forward play orwith LSB of a bit string for the reverse play.

According to another variant of the above digital audio playingapparatus, a shuttle play control unit is also provided. The converterrestores the audio data from the basic format to the specific one bychanging the number of samples per field and number of bits per samplein combination while maintaining the total number of bits per fieldwhich depends upon the product of the number of samples per field andnumber of bits per sample. For shuttle play of audio data of differentfields, the shuttle play control unit passes, to the output unit, onlyvalid ones, including a correct bit string, of the samples restored bythe converter to the specific format. Preferably, the shuttle playcontrol unit should pass, to the output unit, substitute samplesobtained by interpolating the valid samples instead of invalid ones,having no correct bit string, of the samples restored to the specificformat. Also, the shuttle play control unit may substitute zero for anincorrect bit string in at least a part of an invalid one, includingcorrect and incorrect bit strings, among the samples restored to thespecific format, and convert the data part into a valid sample beforepassing it to the output unit.

Also the above object can be attained by providing a digital videorecording apparatus including, according to the present invention, aninput unit for accepting video data having a predetermined samplingfrequency and a specific field frequency and arranged in a frame-relatedspecific format and making at least baseband processing of the videodata, a processor designed to process the video data having thepredetermined sampling frequency and a basic field frequency andarranged in a frame-related basic format, and operate with a clockcorresponding to the sampling frequency to compress, and makeerror-corrective encoding of, the video data adapted to the basicformat, an output unit for writing video data output from the processorto a recording medium, and a converter provided between the input andprocessor. When the specific field frequency of the video data isdifferent from the basic one and the specific format of the video datais different from the basic one, the converter converts the samplingfrequency at the ratio between the specific field frequency and basicone while adapting the specific format to the basic one, before passingthe video data to the processor which will operate with a clockcorresponding to the converted sampling frequency to compress, and makeserror-corrective encoding of, the video data adapted to the basicformat.

Specifically, when the specific format coincides with the basic one, theconverter changes the sampling frequency at a ratio between the specificfield frequency and basic one while maintaining the specific format,before passing the video data to the processor. More specifically, whenthe specific format coincides with the basic one, the converter changesthe sampling frequency by adjusting the invalid data not included in theframe while maintaining the specific format with the valid data includedin the frame being kept as it is. When the specific format is differentfrom the basic one, the converter converts the specific format to thebasic one and then changes the sampling frequency at a ratio between thespecific and basic field frequencies before passing the video data tothe processor. More particularly, when the number of lines of dataincluded in the specific-formatted frame is different from that in thebasic-formatted frame, the converter converts the specific format to thebasic one by adjusting the number of lines in the data included in theframe.

Also the above object can be attained by providing a digital videoplaying apparatus including, according to the present invention, aninput unit for reading, from a recording medium, video data having asampling frequency and specific field frequency and adapted to aframe-related basic format, a processor designed to process video datahaving a predetermined sampling frequency and basic field frequency andarranged in the basic format, and operate with a clock corresponding tothe sampling frequency to make error-corrective decoding of, and expand,the video data adapted to the basic format, an output unit for making atleast baseband processing of video data output from the processor andsupplying the video data to a playback device, and a converter providedbetween the processor and output unit. The processor can operate with aclock corresponding to the sampling frequency of the read video data tomake error-corrective decoding of, and expand, the video data adapted tothe basic format. When the specific field frequency of the read videodata is different from the basic one and the specific format isdifferent from the basic one, the converter restores the video data onceadapted to the basic format back to the specific format, converts thesampling frequency of the read video data and basic one into thepredetermined sampling frequency at a ratio between the specific fieldfrequency before passing the video data to the output unit.

Specifically, when the specific format is the same as the basic one, theconverter passes the video data to the output unit after converting thesampling frequency at a ratio between the specific and basic fieldfrequencies while maintaining the specific format. More specifically,when the specific format is the same as the basic format, the converterconverts the sampling frequency by adjusting the invalid data notincluded in the frame while maintaining the specific format with thevalid data included in the frame being kept at it is. When the specificformat is different from the basic format, the converter passes thevideo data to the output unit after restoring the video data onceadapted to the basic format to the specific format and then convertingthe sampling frequency at a ratio between the specific and basic fieldfrequencies. For example, when the number of lines of data included inthe specific-formatted frame is different from that of data included inthe basic-formatted frame, the converter restores the video data to thespecific format by adjusting the number of lines of the data included inthe frame.

The audio data will be processed as follows. In the recorder section ofthe apparatus, the clock for the audio processor which is a block nearerfrom the audio data converter to a recording medium to or from whichdata is to be written or read is a clock corresponding to a ratio infield frequency between the basic apparatus and an apparatus implementedbased on the basic apparatus (will also be referred to as “intendedapparatus” hereunder). For example, it is assumed that a VTR for audiodata of 60 fields/sec in field frequency and 48 kHz in audio processingclock frequency is a basic apparatus. In this case, the audio processingclock frequency for a VTR implemented, based on the basic apparatus, towrite and read audio data having the field frequency of 50 fields/sec is48 kHz×50/60(=40 kHz).

The audio processing clock to a block nearer from the audio dataconverter to the input unit of the apparatus (farther from the recordingmedium) is an input clock frequency to the apparatus. For example, it isassumed that a 50-fields/sec apparatus implemented, based on the basicapparatus for data having a field frequency of 60 fields/sec and aformat of 800 samples/field×24 bits/sample (with sampling frequency of48 kHz), records audio data in a format of 960 samples/field×20bits/sample (with sampling frequency of 48 kHz). In this case, the clockfor both blocks nearer from the audio data converter to the input unitof the apparatus (farther from the recording medium) is a clock of 48kHz. Therefore, both the basic and intended apparatuses make basebandprocessing of the audio data with 48 kHz and can share the same circuit.

In a block of the audio data converter nearer to the input unit of theapparatus (farther from the recording medium), audio data is processedto have such a number of samples per field and number of bits per samplethat the total number of bits per field is the same as in an apparatusfor audio data of the basic field frequency. For example, it is assumedthat audio data has been recorded in a format of 800 samples/field×24bits/sample by an apparatus for audio data having the basic fieldfrequency of 60 fields/sec. In this case, an apparatus for audio datahaving a field frequency of 50 fields/sec will record audio data in aformat of 960 samples/field×20 bits/sample. The total number of bits perbit for both the apparatuses is 19200 bits/sec. The input samplingfrequency for the intended apparatus can be made the same as that in thebasic apparatus by changing the number of bits per sample from that inthe basic apparatus as in this example. In this example, the samplingfrequency in both the apparatuses for the field frequencies of 60 and 50fields/sec, respectively, is 48 kHz.

The number of samples per field and number of bits per sample for ablock of the audio data converter nearer to the input unit of theapparatus are determined as above. When they are the same as those forthe input unit of the apparatus, they can easily be determined. For aconvenience of the intended field frequency, however, there are notavailable any suitable number of samples per field and number of bitsper sample in some cases. Also, for a convenience of an intendedapparatus, the number of samples per field and number of bits per samplefor the input unit of the apparatus should desirably be arbitrary insome cases, In such a case, there will be determined such a number ofsamples per field (will affect the sampling frequency) and number ofbits per sample as will be approximate to those for the input unit ofthe apparatus and the same as the total number of bits of audio data forthe basic apparatus. To obtain that sampling frequency, an audiosampling converter is provided between the input unit of the apparatusand audio data converter. For example, it is assumed here that a basic60-fields/sec apparatus can record audio data in a format of 800samples/field×24 bits/sample and a 48-fields/sec apparatus, implementedbased on the 60-fields/sec apparatus as a basic apparatus, is for audiodata having a sampling frequency of 48 kHz. For the 48-fields/secapparatus, audio data includes 1000 samples per field. A simplecalculation provides a format of 1000 samples/field×19.2 bits/samplebecause 800 samples/field×24 bits/sample=19200 bits/field. However,since the “19.2 bits/sample” is not any integer, this data format cannotbe adopted. For a solution, the number of bits/sample is made aconvenient one approximate to “19.2”. For example, the format is made“960 samples/field×20 bits/sample”. However, this number of samples perfield leads to a sampling frequency of 960 samples/field×48 fields/sec(=46080 samples/sec). To solve this problem, there is provided betweenthe input unit and audio data converter of the apparatus a sampling rateconverter for 46.08 kHz and 48 kHz for an input unit sampling rate to be48 kHz as desired. In this case, since the audible range of sound to thehuman being is generally 20 kHz, the sampling rate has only to be over40 kHz according to the theory of sampling. Also, the sampling rate of46.08 kHz is considered to be sufficient in view of the performances ofthe D-A converter, A-D converter, etc. used in the apparatus.

In case there are not available any convenient number of samples perfield and convenient number of bits per sample, the total number of bitsmay be attained which is the same as for the basic apparatus by adding astuffing (meaningless data) to the data without using the sampling rateconverter. For example, in the 48-fields/sec apparatus, a stuffing(meaningless data) of 200 bits is added to the data in a format of 1000fields/sample×19 bits/sample to convert the format to 800samples/field×24 bits/sample(=19200 bits/field).

In the digital audio recording apparatus according to the presentinvention, the format of audio data can also be converted in an ECCencoding circuit. For the audio data format conversion, only an audioclock used in the baseband processing is supplied to the ECC encodingcircuit. For example, for implementing a 50-fields/sec VTR operatingwith an audio baseband precessing clock of 48 kHz based on a VTR takenas a basic apparatus and directed for audio data having a fieldfrequency of 60 fields/sec and audio baseband processing clock of 48kHz, only the clock of 48 kHz is supplied as the audio clock withoutinput of 48 kHz×50/60(=40 kHz).

The format conversion of audio data should be done just after the audioclock is supplied to the ECC encoding circuit. For the conversion of theaudio data format, as many registers as the number of bits per audiobaseband sample in the basic recording apparatus and audio data iscyclically written to and read from the registers in an LSB-first orMSB-first manner. Also, at the reading side, a pause is taken formatching with a data rate at the writing side. For example, to implementan apparatus for data having a field frequency of 50 fields/sec and aformat of 960 samples/field×20 bits/sample based on an apparatus takenas a basic apparatus and directed for data having a field frequency of60 fields/sec and a format of 800 samples/field×24 bits/sample, twentyfour registers (for 24 bits) are provided in the ECC encoding circuitand audio data is cyclically written with LSB first to the registers ata rate of 20 bits/sample and the audio data is read with LSB first fromthe registers at a rate of 24 bits/sample to convert the format of theaudio data. At the reading side, a pause is taken at every six samples.

The circuit control effected after the audio data formation conversionlasts correspondingly to reading data from an audio data formatconversion register. That is, correspondingly to the pause in readingthe audio data from the audio data format conversion register, theinternal counter for the control signal is put out of countingoperation. For example, for implementing a 50-fields/sec apparatus basedon a 60-fields/sec apparatus taken as a basic apparatus, reading of theaudio data from the audio data conversion register is not done at everysix samples. Correspondingly, the internal counter for the controlsignal is also put out of counting operation. Thus, the period of thecontrol signal will be 6/5 of 60 fields/sec and hence a processing at arate of 800 samples per field in the 60-fields/sec apparatus will bemade at a rate of 960 samples per field in the 50-fields/sec apparatus.

In the digital audio playing apparatus according to the presentinvention, the clock for the audio processor in a block nearer from theaudio data converter to a recording/playing medium is a onecorresponding to a ratio in field frequency between the basic apparatusand intended apparatus. For example, when a VTR for audio data having afield frequency of 60 fields/sec and audio processing clock frequency of48 kHz is a basic apparatus, the audio processing clock frequency of aVTR implemented, based on the basic apparatus, for audio data having afield frequency of 50 fields/sec is 48 kHz×50/60(=40 kHz).

The audio processing clock for a block nearer from the audio dataconverter to the output unit of the apparatus (farther from the medium)is an output clock frequency of the apparatus. For example, it isassumed that based on a 60-fields/sec apparatus for audio data having aformat of 800 samples/field×24 bits/sample (with sampling frequency of48 kHz), a 50-fields/sec apparatus is implemented to record audio datahaving a format of 960 samples/field×20 bits/sample (with samplingfrequency of 48 kHz). In this case, the clock for a block nearer fromthe audio data converter to the output unit of the apparatus (fartherfrom the medium) is 48 kHz. Thus, both the 60- and 50-fields/secapparatuses make baseband processing of the audio data with 48 kHz andcan share the same circuit.

In a block of the audio data converter nearer to the output unit of theapparatus (farther from the recording medium), audio data is processedto have such a number of samples per field and number of bits per samplethat the total number of bits per field is the same as in an apparatusfor audio data of the basic field frequency. For example, it is assumedthat audio data has been recorded in a format of 800 samples/field×24bits/sample by an apparatus for audio data having the basic fieldfrequency of 60 fields/sec. In this case, an apparatus for audio datahaving a field frequency of 50 fields/sec will record audio data in aformat of 960 samples/field×20 bits/sample. The total number of bits perbit for both the apparatuses is 19200 bits/sec. The output samplingfrequency for the intended apparatus can be made the same as that in thebasic apparatus by changing the number of bits per sample from that inthe basic apparatus as in this example. In this example, the samplingfrequency in both the apparatuses for the field frequencies of 60 and 50fields/sec, respectively, is 48 kHz.

The number of samples per field and number of bits per sample for ablock of the audio data converter nearer to the output unit of theapparatus are determined as above. When they are the same as those forthe output unit of the apparatus, they can easily be determined.Depending upon an intended field frequency, however, there are notavailable any suitable number of samples per field and number of bitsper sample in some cases. Also, for a convenience of the intendedapparatus, the number of samples per field and number of bits per samplefor the output unit of the apparatus should desirably be arbitrary insome cases. In such a case, there will be determined such a number ofsamples per field (will affect the sampling frequency) and number ofbits per sample as will be approximate to those for the output unit ofthe apparatus and the same as the total number of bits of audio data forthe basic apparatus. To obtain that sampling frequency, an audiosampling converter is provided between the output unit of the apparatusand audio data converter. For example, it is assumed here that a basic60-fields/sec apparatus can record audio data in a format of 800samples/field×24 bits/sample and a 48-fields/sec apparatus, implementedbased on the 60-fields/sec apparatus as a basic apparatus, is for audiodata having a sampling frequency of 48 kHz. For the 48-fields/secapparatus, audio data includes 1000 samples per field. A simplecalculation provides a format of 1000 samples/field×19.2 bits/samplebecause 800 samples/field×24 bits/sample=19200 bits/field. However,since the “19.2 bits/sample” is not any integer, this data format cannotbe adopted. For a solution, the number of bits/sample is made aconvenient one approximate to “19.2”. For example, the format is made“960 samples/field×20 bits/sample”. For this number of samples perfield, however, the sampling frequency will be 960 samples/field×48fields/sec(=46080 samples/sec). To this end, there is provided betweenthe output unit and audio data converter of the apparatus a 46.08/48-kHzsampling rate converter and the output unit sampling rate is 48 kHz asdesired. In this case, the sampling frequency is converted to 46.08 kHzbut since the audible range of sound to the human being is generally 20kHz, the sampling rate has only to be over 40 kHz according to thetheory of sampling. Also, the sampling rate of 46.08 kHz is consideredto be sufficient in view of the performances of the D-A converter, A-Dconverter, etc. used in the apparatus.

In case there are not available any convenient number of samples perfield and convenient number of bits per sample, the total number of bitsmay be attained which is the same as for the basic apparatus by adding astuffing (meaningless data) to the data without using the sampling rateconverter. For example, in the 48-fields/sec apparatus, a stuffing(meaningless data) of 200 bits is added to the data in a format of 1000samples/field×19 bits/sample to convert the format to 800samples/field×24 bits/sample(=19200 bits/field).

At the time of data encoding during data recording, the audio data forthe intended apparatus is converted by the audio data converter into aone having the same number of samples/field and number of bits/sample asthose in the baseband of the basic apparatus while changing the samplingrate at the field frequency ratio between the intended and basicapparatuses. Specifically, FIFO can be used for this data conversion andalso for the sampling frequency conversion. For example, it is assumedhere that the basic apparatus is for audio data having a field frequencyof 60 fields/sec and a format of 800 samples/field×24 bits/sample and anintended apparatus implemented based on the basic apparatus recordsaudio data having a field frequency of 50 fields/sec in a format of 960samples/field×20 bits/sample. In the 50-fields/sec apparatus, sixsamples are processed as one unit, six samples×20 bits/sample (withsampling frequency of 48 kHz) are written to FIFO of the audio dataconverter, and the five samples×24 bits/sample are subject to datarearrangement in FIFO to read audio data with 40 kHz(=48 kHz×50/60).Thus, the audio data converter can converts 960 samples/field×20bits/sample (with sampling frequency of 48 kHz) into 800samples/field×24 bits/sample (with sampling frequency of 40 kHz).

For encoding during data recording, audio data for an intended apparatusis converted by the audio data converter to have the same number offields per field and number of bits per sample as those for basebandprocessing in an apparatus accommodating the basic field frequency andsimultaneously the sampling rate is multiplied by a ratio in fieldfrequency between both the apparatuses. More specifically, FIFO can beused for the data conversion and also the sampling frequency isconverted by the FIFO. For example, it is assumed that the basicapparatus deals with a field frequency of 60 fields/sec and reproducesaudio data having a format of 800 samples/field×24 bis/sample and a50-fields/sec apparatus is implemented, based on the basic apparatus, torecord the audio data in a format of 960 samples/field×20 bits/sample.In this case, the recording medium has recorded therein the audio datawhose format of 6 samples×20 bits/sample (with sampling frequency of 48kHz) has been converted to 5 samples×24 bits/sample (with samplingfrequency of 40 kHz). The audio data including 5 samples×24 bits/sample(with sampling frequency of 40 kHz), read from the medium, is written toFIFO in the audio data converter with 40 kHz. In FIFO, the audio data isrearranged in the format of 6 samples×20 bits/sample and read with asampling frequency of 48 kHz. Thus, the audio data converter can convertthe format of 800 samples/field×24 bits/sample (with sampling frequencyof 40 kHz) into 960 samples/field×20 bits/sample (with samplingfrequency of 48 kHz).

The sequence of the audio data conversion starts with the first samplein the beginning of the field. In the above example, for example, the 6samples×20 bits/sample from the first sample in the beginning of thefield at the time of encoding is converted to 5 samples×24 bits/sample,while the 5 samples×24 bits/sample from the first sample in thebeginning of the field at the time of decoding is converted to 6samples×20 bits/sample.

The audio recording format on the medium is made the same as in thebasic apparatus, and also the error-corrective processing is made thesame as in the basic apparatus. In case the basic 60-fields/secapparatus is for audio data of 800 samples/field×24 bits/sample and a50-fields/sec apparatus implemented based on the basic apparatus is torecord the audio data in a format of 960 samples/field×20 bits/sample,the audio data is converted in format from 960 samples/field×20bits/sample into 800 samples/field×24 bits/sample. The audio data thusconverted has the same number of samples per field and the same numberof bits per sample as those in the basic apparatus, and the sameerror-corrective processing as in the basic apparatus is effected on theaudio data to record the audio data in the same audio recording formatas in the basic apparatus.

In the digital audio recording apparatus according to the presentinvention, the format of audio data can also be converted in an ECCdecoding circuit. For the audio data format conversion, only an audioclock used in the baseband processing is supplied to the ECC decodingcircuit. For example, for implementing a 50-fields/sec VTR operatingwith an audio baseband precessing clock frequency of 48 kHz based on aVTR taken as a basic apparatus and directed for audio data having afield frequency of 60 fields/sec and audio baseband processing clockfrequency of 48 kHz, only the clock of 48 kHz is supplied as the audioclock without input of 48 kHz×50/60(=40 kHz).

The format conversion of audio data should be done just before the audioclock is outputted from the ECC decoding circuit. For the conversion ofthe audio data format, as many registers as the number of bits per audiobaseband sample in the basic playing apparatus and audio data iscyclically written to and read from the registers in an LSB-first orMSB-first manner. Also, at the writing side, a pause is takenappropriately in writing for matching with a data rate at the readingside. For example, to implement a 50-fields/sec apparatus for data aformat of 960 samples/field×20 bits/sample based on a 60-fields/secapparatus taken as a basic apparatus and directed for data having aformat of 800 samples/field×24 bits/sample, twenty four registers (for24 bits) are provided in the ECC decoding circuit and audio data iscyclically written with LSB first to the registers at a rate of 24bits/sample and the audio data is read with LSB first from the registersat a rate of 20 bits/sample to convert the format of the audio data. Atthe writing side, a pause is taken at every six samples.

The circuit control effected before the audio data formation conversionlasts correspondingly to a pause in writing the audio data to an audiodata format conversion register. That is, correspondingly to the pausein writing the audio data to the audio data format conversion register,the internal counter for the control signal is put out of countingoperation. For example, for implementing a 50-fields/sec apparatus basedon a 60-fields apparatus as a basic apparatus, writing the audio data tothe audio data conversion register is not done at every six samples.Correspondingly, the internal counter for the control signal is also putout of counting operation. Thus, the period of the control signal willbe 6/5 of 60 fields/sec and hence a processing at a rate of 800 samplesper field in the 60-fields/sec apparatus will be made at a rate of 960samples per field in the 50-fields/sec apparatus.

Audio data is read from or written to the format conversion registerwith LSB or MSB first whichever is automatically selected depending uponwhether the forward or reverse play is to be done. Since the arrivingorder of the audio data intended for the forward play is opposite tothat of the audio data for the reverse play, the format conversion ismade with MSB first or LSB first depending upon the play is made forwardor reverse. Thus, it is necessary to appropriately control the formatconversion for the MSB first mode or LSB first mode depending uponwhether the audio data is reproduced forward or reverse.

In the shuttle play, audio data including data of different fields mixedwhen the audio data undergoes the format conversion is reproduced butsince each of the first and last data packs in the sequence of audiodata conversion should include all data for one original sample, onlyformat-convertible data included in the original data is reproduced asinvalid data. The data other than the first and last data in thesequence of audio data conversion cannot completely be converted informat and a mixture of different sample data is converted. The sampledata is taken as an error and concealed at the later stage of operation.It should be noted that since valid audio data format-converted samplesare formed in addition to the first and last data in the sequence ofaudio data conversion by limiting the number of high-order valid databits, more data than above can be used as valid data for shuttle-playsound. In this case, however, LSBs lower than the limited bits arereplaced with 0 data.

In the digital video recording apparatus according to the presentinvention, the video frame of an input signal having an object fieldfrequency is converted by the converter to be the same as the frame inthe basic apparatus and also the clock is converted by multiplying it bythe field frequency ratio between the object and basic apparatuses. Forexample, it is assumed here that the basic apparatus accommodates videodata having a field frequency of 60 fields/sec and a format of 2200samples/line×1125 lines/field (with effective area of 1920 samples×1080lines and clock of 74.25 MHz) and the intended apparatus accommodatesvideo data having a field frequency of 50 fields/sec and a format of2640 samples/line×1125 lines/field (with effective area of 1920samples×1080 lines and clock of 74.25 MHz). In this case, the format of2640 samples/line×1125 lines/field (with effective area of 1920samples×1080 lines and clock of 74.25 MHz) is converted to the format of2200 samples/line×1125 lines/field (with effective area of 1920samples×1080 lines and clock of 61.875 MHz(=74.25 MHz×50/60)).

In the circuit provided downstream of the converter, the video encodingincluding video compression, error-corrective encoding, etc. in theintended apparatus is quite the same as that in the basic apparatusexcept for a clock multiplied by the field frequency ratio between thebasic and intended apparatuses. For example, when the basic apparatusaccommodates video data having a field frequency of 60 fields/sec and avideo compression output clock of 46.4 MHz and the intended apparatusaccommodates a field frequency of 50 fields/sec, the intended apparatuswill do the same as the basic apparatus with a video compression outputclock of 46.4 MHz×50/60(=38.6666 MHz).

On the other hand, down to the video decoding clock converter of thedigital video playing apparatus, the video decoding including theerror-corrective decoding, video expansion, etc. is quite the same asthat in the basic apparatus with a clock multiplied by the fieldfrequency ratio between the basic and intended apparatuses. For example,when the basic apparatus accommodates video data having a fieldfrequency of 60 fields/sec and a video expansion input clock of 46.4 MHzand the intended apparatus accommodates a field frequency of 50fields/sec, the intended apparatus will do the same as the basicapparatus with a video expansion input clock of 46.4 MHz×50/60(=38.6666MHz).

In the video decoding clock converter, the video frame of an outputsignal of the object field frequency is converted into a desired frameand also the clock is converted into a desired one. For example, it isassumed here that the basic apparatus accommodates video data having afield frequency of 60 fields/sec and a format of 2200 samples/line×1125lines/field (with effective area of 1920 samples×1080 lines and clock of74.25 MHz) and the output from the intended apparatus has a fieldfrequency of 50 fields/sec and a format of 2640 samples/line×1125lines/field (with effective area of 1920 samples×1080 lines and clock of74.25 MHz). In this case, since at the input side of the video decodingclock converter, the same frame and clock as those in the basicapparatus are ones multiplied by the field frequency ratio between thebasic and intended apparatuses, the format of data for the basicapparatus is 2200 samples/line×1125 lines/field (with effective area of1920 samples×1080 lines and clock of 61.875 MHz(=74.25 MHz×50/60)) andthis is converted to the format of 2640 samples/line×1125 lines/field(with effective area of 1920 samples×1080 lines and clock of 74.25 MHz)for the intended apparatus.

In case the number of video lines and effective frame vary betweenstandards (SD) or the like as well as field frequencies, the recordersection has provided in the encoding system of the intended apparatus aconverter having a video line convert filter and which makes the numberof video line and effective frame the same as those in the basicapparatus and coverts the clock by multiplying it by the ratio in fieldfrequency between the basic and intended apparatuses. For example, it isassumed here that one of the basic and intended apparatuses accommodatesvideo data having a field frequency of 60 fields/sec and a format of 720samples×480 lines (13.5 MHz) and the other accommodates video datahaving a field frequency of 50 fields/sec and a format of 720samples×576 lines (13.5 MHz), thus these video data being different inframe and clock from each other. In this case, the data of 50 fields/secand 720 samples×576 lines is line-converted by filtering into 60fields/sec and 720 samples×480 lines and the clock frequency isconverted into 13.5 MHz×50/60(=11.25 MHz).

In case the number of video lines and effective frame vary betweenstandards (SD) or the like as well as field frequencies, the playersection has provided in the decoding system of the intended apparatus aconverter having a video line convert filter and which converts a videosignal whose video frame and clock are multiplied by the field frequencyratio between the basic and intended apparatuses into a one having adesired video frame clock frequency. For example, it is assumed herethat the basic apparatus accommodates video data having a fieldfrequency of 60 fields/sec and a format of 720 samples×480 lines (13.5MHz) and the other accommodates video data having a field frequency of50 fields/sec and a format of 720 samples×576 lines (13.5 MHz). In thiscase, the video frame at the input side of the converter with the videoline convert filter has the same clock as for the basic apparatus andthe clock multiplied by the field frequency ratio between the basic andintended apparatuses. So, the video data for the intended apparatus hasa format of 720 samples×480 lines (with clock of 11.25 MHz (=13.5MHz×50/60)). This is converted by the converter with the video lineconvert filter into the format of 720 samples×576 lines (with clockfrequency of 13.5 MHz.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are block diagrams showing together an example of thebasic digital audio recorder/player.

FIG. 2 schematically illustrates audio data serially supplied to thebasic digital audio recorder/player in FIGS. 1A and 1B.

FIGS. 3A and 3B show a format of video data.

FIGS. 4A and 4B show a format of audio data.

FIGS. 5A and 5B are block diagrams showing together a first embodimentof the digital audio/video recorder/player according to the presentinvention.

FIGS. 6A, 6B and 6C explain together the operations of the digitalaudio/video recorder/player shown in FIGS. 5A and 5B.

FIGS. 7A and 7B explain together the operations of an audio data packingunit included in the digital audio/video recorder/player shown in FIGS.5A and 5B.

FIGS. 8A and 8B explain together the operations of an audio datadepacking unit included in the embodiments of digital audio/videorecorder/player shown in FIGS. 5A and 5B.

FIGS. 9A and 9B are block diagrams showing together a second embodimentof the digital audio/video recorder/player according to the presentinvention.

FIGS. 10A, 10B and 10C explain together the operations of the digitalaudio/video recorder/player shown in FIGS. 9A and 9B.

FIGS. 11A and 11B are block diagrams showing together another example ofthe basic digital audio/video recorder/player FIGS. 12A and 12B areblock diagrams showing together a third embodiment of the digitalaudio/video recorder/player according to the present invention.

FIGS. 13A, 13B and 13C explain together the operations of the digitalaudio/video recorder/player shown in FIGS. 12A and 12B.

FIGS. 14A and 14B are block diagrams showing together a fifth embodimentof the digital audio/video recorder/player according-to the presentinvention.

FIG. 15 is a block diagram showing the construction of an ECC encoderand audio/video coupler included in the digital audio/videorecorder/player shown in FIGS. 14A and 14B.

FIG. 16 explains the operations of the ECC encoder and audio/videocoupler included in the digital audio/video recorder/player shown inFIGS. 14A and 14B.

FIG. 17 explains the operations of a convert register included in theECC encoder and audio/video coupler shown in FIG. 16.

FIG. 18 is a block diagram showing the construction of an ECC decoderand audio/video separator included in the digital audio/videorecorder/player shown in FIGS. 14A and 14B.

FIG. 19 explains the operations of the ECC decoder and audio/videoseparator included in the digital audio/video recorder/player shown inFIGS. 14A and 14B.

FIGS. 20A and 20B explain the operations of the convert registerincluded in the ECC decoder and audio/video separator included shown inFIG. 19.

FIG. 21 shows an example of shuttle-play operation made in the digitalaudio/video recorder/player shown in FIGS. 14A and 14B.

FIG. 22 shows another example of shuttle-play operation made in thedigital audio/video recorder/player shown in FIGS. 14A and 14B.

BEST MODE FOR CARRYING OUT THE INVENTION

As previously mentioned, the present invention is directed to asimplified recording/playing apparatus for audio and video data of afield frequency, implemented, based on an existing recording/playingapparatus taken as a basic apparatus and directed for audio data andvideo data of a different field frequency, to record or reproduce audioand vide data originated from the basic apparatus . In the followingexplanation, a VTR (video tape recorder) will be taken as an example ofsuch an audio/video recorder/player, and hence the audio/videorecorder/player will be referred to simply as “VTR”. However, it shouldbe noted that the present invention is not limited to the VTR. The VTRincorporates a CPU (central processing unit) which executes a computerprogram to carry out an audio recording method, audio playing method,video recording method and a video playing method, each including apredetermined sequence of operations. The computer program is stored ina ROM (read-only memory), hard disc or any other recording medium andinstalled into the VTR. The CPU in the VTR will read the computerprogram from such a medium and execute it.

FIGS. 1A and 1B are block diagrams, respectively, showing a VTR capableof supporting a field frequency of 60 fields/sec. The VTR is the “basicapparatus” referred to herein. FIG. 1A shows the recorder section of theVTR and FIG. 1B shows the player section. An input video signal issupplied to a video baseband processor 1 which operates with a clock of74.25 MHz. The video baseband processor 1 processes a brightnesscomponent, chroma component, etc. of the input video signal. The videosignal thus processed by the video baseband processor 1 is sent to avideo compressor 2 where the video signal will be compressed and carriedon a clock of 46.4 MHz to an ECC encoder and audio/video coupler 4.

On the other hand, the input audio signal to the VTR has a samplingfrequency of 48 kHz. The number of samples per field is 48000/60=800.One sample is of 24 bits. The input audio signal is sent to an audiobaseband processor 3 where it will undergo an audio baseband processing.For example, the audio baseband processor 3 controls the gain etc. ofthe audio signal. The audio signal thus processed by the audio basebandprocessor 3 is sent to the ECC encoder and audio/video coupler 4 whichwill process the audio and video signals compliance with a VTR tapeformat by generating an error correction code (ECC) for each of theaudio and video signals and adding parities C1 and C2 to the ECC codesthus generated, respectively. The input clocks of the ECC encoder andaudio/video coupler 4 operates with a clock of 46.4 MHz for the videosignal and a clock of 48 kHz for the audio signal to output a serialdata of 94 MHz for tape recording.

As above, the audio input data to the ECC encoder and audio/videocoupler 4 is a serial one and supplied at a rate of 64 bits/sample. FIG.2 shows a format of the audio serial data. As will be seen, the serialdata is supplied in a mixed 2-channel AES/EBU form. In FIG. 2, Z, M, J,E, V, U, C and P are flags. The main data is supplied with LSB first.FIG. 2 shows data formats of 24 bits/sample and 20 bits/sample,respectively. Thus, the audio data to the ECC encoder and audio/videocoupler 4 is a serial data. In FIGS. 1A and 1B, “48 kHz” means a rate of48 kHz when one sample is counted as one clock, namely, it is a samplingfrequency. Since the audio input to the ECC encoder and audio/videocoupler 4 is a serial data, so the clock frequency of the serial datawill be represented by 48 kHz×64 bits/sample=3.072 MHz. For the audiodata, however, the sampling frequency in which one sample is taken asone unit is important. One sample is supplied as a series of 64 bits inthis example, but it will be supplied as a series of 256 bits as thecase may be. Therefore, only “48 kHz” which is thus important is shownin FIGS. 1A and 1B, and the audio clock will be indicated with thesampling frequency hereafter.

The signal output from the ECC encoder and audio/video coupler 4 will berecorded to a tape. A signal read from the tape is supplied to an ECCdecoder and audio/video separator 5. After separating the signal readfrom the tape into audio and video data, the ECC decoder and audio/videoseparator 5 will make error-corrective decoding of the ECC code. Thevideo data is supplied synchronously with a clock of 46.4 MHz to a videoexpander 6 where it will be decompressed or expanded to provide a videobaseband signal. The video baseband signal is sent to a video basebandprocessor 7. The brightness component, chroma component, etc. of thevideo baseband signal, are processed by the video baseband processor 7and the video baseband signal thus processed is provided as an outputfrom the VTR. On the other hand, the audio signal undergo an errorcorrection in the ECC decoder and audio/video separator 5 and isprovided as an audio baseband signal from the ECC decoder andaudio/video separator 5. The audio signal output from the ECC decoderand audio/video separator 5 includes 800 samples per field and 24 bitsper sample. The audio signal is sent at a sample frequency of 48 kHz toan audio baseband processor 8 where it will undergo gain control andother processing. This signal is an output audio signal from the VTR.

FIG. 3A shows a format in which video recording is done at a fieldfrequency of 60 fields/sec. One field is composed of six tracks eachforming one ECC (error correction code) block (product code). Becauseone field includes six tracks, video data has 6 ECC blocks per field. InFIG. 3A, the “V” in the tape footprint indicates “video” and one videois divided in two sectors per track. One ECC block of the video is of250 syncs per track, namely, 125 syncs per sector. That is, one trackincludes 250-sync data. This ECC block is constructed as shown in FIG.3B. One sync means one C1-directional data in the ECC block. The 1C ECCparity is of 12 bytes while the C2 ECC parity is of 24 bytes. Video datais compressed one.

FIGS. 4A and 4B show together a recording format for audio data havingthe field frequency of 60 fields/sec. The “A0” in the tape footprintshown in FIG. 4A indicates an audio channel 0, “A1” indicates an audiochannel 1, “A2” indicates an audio channel 2, and “A33 ” indicates anaudio channel 3. The audio ECC block includes one field per audiochannel. The audio is recorded at a rate of 4 syncs/audio channel.Therefore, data on six channels for one field will totally be 4syncs/track•channel×6 tracks/field=24 syncs/field•channel. The audio ECCblock is constructed as shown in FIG. 4B. Twelve bytes are allocated tothe C1 ECC parity and also 12 bytes are allocated to the C2 ECC parity.Since one audio sample is of 24 bits, so this number of bits is dividedinto 8 bits×3 symbols. As shown in FIG. 4B, one sample is constructed tobe put as a 3-bit data into one sync with MSB first. Since one fieldincludes 800-sample data, so a data frame for four samples is excessivein the ECC block but user data is allocated to the data frame.Non-compressed data is put in the audio sample data.

FIGS. 5A and 5B are block diagrams showing together a 50-fields/sec VTR.FIG. 5A shows the recorder section and FIG. 5B shows the player section.This VTR is constructed to accommodate data originated from the60-fields/sec VTR shown in FIGS. 1A and 1B. This 50-fields/sec VTR usesblocks including a video compressor 2, audio baseband processor 3, ECCencoder and audio/video coupler 4, ECC decoder and audio/video separator5, video expander 6 and an audio baseband processor 8, all of which arethe same as those used in the 60-fields/sec VTR. A video basebandprocessor 1′ and video baseband processor 7′ are provided for videoencoding and decoding, respectively, with a clock frequency of 74.25 MHzwhich is the same clock as for the 60-fields/sec video basebandprocessor 1 and video baseband processor 7 and almost the sameprocessing as by the latter. Therefore, there is little actualdifference in circuit between the video baseband processor processors 1′and 1 and the video baseband processors 7′ and 7, respectively.

The recorder section of this VTR includes a video clock converter 11which is supplied with an input sampled with 74.25 MHz and provides anoutput of 61.875 MHz(=50/60 in field frequency ratio×74.25 MHz). Thisexample is of a “Hi-Vision” type. Whether the field frequency is 50 Hzor 60 Hz, the effective frame area is of 1920 samples×1080 lines (or1440 samples×1080 lines). That is, since there is no difference ineffective frame between the cases of 50 and 60 Hz, so the output of61.875 MHz being 50/60 of the input can be obtained just by discardingthe ineffective frame area and the entire effective frame area can bevalid data as it is.

FIGS. 6A, 6B and 6C show differences among frames of different fieldfrequencies in different processing steps. FIG. 6A shows a frame whosefield frequency is 60 Hz, FIG. 6B shows a frame whose field frequency is50 Hz, and FIG. 6C shows a frame (signal form) resulted from processingof the 50-Hz frame by the video clock converter 11. The signal form (asin FIG. 6C) after processed by the video clock converter 11 is quite thesame, including the ineffective frame area, as the signal form (as inFIG. 6A) of which the field frequency is 60 fields/sec and samplingfrequency is 74.25 MHz.

The 61.875-MHz signal output from the video clock converter 11 is sentto the video compressor 2. Under the assumption that the output clock is38.666 MHz which is 50/60 of 46.4 MHz, the clock and data rate for thevideo compressor 2 are just 50/60 of the corresponding basic clock anddata rate, respectively, and necessary operations are quite the same asin the 60-fields/sec VTR which is the base of this 50-fields/sec VTR. Inother words, the video clock converter 11 plays a role in causing thesystem components provided downstream thereof to make quite the sameoperations as in the 60-fields/sec VTR at the rate of 50/60 in thelatter VTR.

In the audio system, an audio data packing unit 9 is provided whichfunctions the same way as the video clock converter 11. As shown in FIG.5A, the audio data packing unit 9 converts data whose sampling frequencyis 48 kHz and format is 960 samples/field×20 bits/sample(=19200bits/field) into a data whose sampling frequency is 40 kHz and format is800 samples/field×24 bits/sample(=19200 bits/field). Since both theseaudio data have the same total number of bits per field(=19200bits/field), so they can be converted into each other. It should benoted here that since 40 kHz =48 kHz×50/60, so the components provideddownstream of the audio data packing unit 9 can also function in thesame manner as in the 60-fields/sec VTR at the rate of 50/60 in thelatter VTR.

FIG. 7A shows the audio data packing unit 9 in detail. As shown in FIG.7A, the audio data packing unit 9 includes an FIFO and FIFO controller.In the 48-kHz system, one sequence of the data pack includes 6 samples(each including 20 bits). Namely, 20 bits/sample×6 samples=120 bits.This sequence of data is converted in the 40-kHz system into a datasequence of 120 bits(=24 bits/sample×5 samples). The audio data packingunit 9 has serially been supplied with audio data and the data isserially written bit by bit into the FIFO at a frequency of 64×48 kHz inthe 48-kHz system. At this time, flags Z, M, J, E, V, U, C and P are notwritten into the FIFO but solely the data is written into the FIFO. Thewritten data is serially read bit by bit from the FIFO at a frequency of64×40 kHz in the 40-kHz system. However, the flags are not read from theFIFO but “0” is put in place of each flag (the flags are meaninglessdata in the latter downstream section of the system. Data is read at arate of 24 bits/sample and sent to the ECC encoder and audio/videocoupler 4. As shown in FIG. 7B, one sequence starts at the top of afield. For this sequence starting, a signal FIELD-START indicative of afield top is supplied to the audio data packing unit 9. FIG. 7B showshow data is written to and read from the FIFO of the audio data packingunit 9. The FIFO is shown divided in 4-bit blocks for easierunderstanding of how data of 20 bits are converted into data of 24 bits.Actually, data is written and read bit by bit as mentioned above. Forconversion of the 48-kHz system into 40-kHz system, the FIFO controllerprovides a control signal FIELD-START, namely, information indicatingwhere the field top is in the converted data in the 40-kHz system.According to the control signal FIELD-START, the ECC encoder andaudio/video coupler 4 cuts audio data by punctuating it at eachdiscontinuity between the fields in the data to define an ECC block.

The video and audio inputs to the ECC encoder and audio/video coupler 4shown in FIG. 5A have a sampling frequency and format which are 50/60 ofthose in the 60-fields/sec VTR. Since the output from the ECC encoderand audio/video coupler 4 is also 50/60 of that in the 60fields/sec-VTR, so the ECC encoder and audio/video coupler 4 can operatequite the same way as in the 60-fields/sec VTR at the rate of 50/60 ofthat in the latter VTR. Of course, the circuits in the 60-fields/sec VTRcan be quite the same as those in the 50-fields/sec VTR. In the50-fields/sec VTR, data is recorded at the rate of 50/60 of that in the50-fields/sec VTR. At this time, the tape travel speed, drum rotationspeed, etc. are all 50/60 (field frequency ratio) of those in the60-fields/sec VTR. Therefore, there is no different in footprint betweenthe 60- and 50-fields/sec VTRs.

On the other hand, when reading audio and video data from a tape, theECC decoder and audio/video separator 5 is supplied with data (50/60 ofthat in the 60-fields/sec VTR which is the base of the 50-fields/secVTR). Therefore, the 50-fields/sec VTR will output both video and audiodata at the rate of 50/60 of that in the 60-fields/sec VTR. Since theECC decoder and audio/video separator 5 works quite the same way as thatin the 60-fields/sec VTR except for the data rate (50/60 of that in the60-fields/sec VTR), so the ECC decoder and audio/video separator in the60-fields/sec VTR can be used commonly between the 50- and 60-fields/secVTRs. The output from the ECC decoder and audio/video separator 5 issupplied to the video expander 6. Both input to and output from thevideo expander 6 are made at the rate of 50/60 of that in the60-fields/sec VTR. Naturally, the circuit of the video expander 6 in the50-fields/sec VTR is quite the same as that in the 60-fields/sec VTR.The video clock converter 12 in the player section works reversely tothe video clock converter 11 in the recorder section. The video clockconverter 12 converts an input signal of 61.875 MHz which is 50/60 ofthe signal in the 60-fields/sec VTR back into a signal of 74.25 MHz. Aswill be seen in FIGS. 6B and 6C, the signal has the effective areathereof not changed but the ineffective area (blanking area) thereofchanged to 74.25 MHz. There is provided a video baseband processor 7′which makes a video baseband processing of the input signal adjust thebrightness component, chroma component, etc. of the latter. The videobaseband processor 7′ provides a signal having a field frequency of 50fields/sec as a VTR output.

On the other hand, the audio data undergoes error correction and is thenpacked to be data of 40 kHz and 800 samples/field×24 bits/sample in theECC decoder and audio/video separator 5, and it is supplied to the audiodata depacking unit 10. The audio data depacking unit 10 works reverselyto the audio data packing unit 9 to depack the data for converting itback into data of 48 kHz and 960 samples/field×20 bits/sample. The audiodata depacking unit 10 is illustrated in detail in FIGS. 8A and 8B. Asshown in FIG. 8A, even the video data has been converted from 40 kHz to48 kHz by the FIFO controller as in the audio data packing unit 9, theFIELD-START signal indicative of a field top will correctly betransmitted. The FIELD-START signal in the recording section indicatesthe start point of a data unpack sequence. It is a very importantsignal. As in the audio data packing unit 9, one sequence is 5samples×24 bits/sample=120 bits in the 40-kHz system (recorder section)while being 6 samples×20 bits=120 bits in the 48-kHz system (playersection). Also in the audio data depacking unit 10, the FIELD-STARTsignal indicates the start point of a data unpack sequence.

The audio data of 48 kHz and 960 samples/field×20 bits/sample processedby the audio data depacking unit 10 is supplied to the audio basebandprocessor 8 where it will undergo an audio baseband processing such asgain control etc. The audio data thus processed is supplied as data of50 fields/sec in field frequency, 48 kHz in sampling frequency and 960samples/field×20 bits/sample in format. Thus, the 50-fields/sec VTR isconstructed to accommodate data originated from the 60-fields/sec VTR.

In the foregoing, the present invention has been described concerningthe data having the field frequency of 50 fields/sec. However, thepresent invention is applicable to data having any other fieldfrequency. FIGS. 9A and 9B are block diagrams, respectively, showingtogether a VTR for data of 48 fields/sec in field frequency. FIG. 9Ashows the recorder section of the VTR and FIG. 9B shows the playersection. The base apparatus for this VTR is the 60-fields/sec VTR havingbeen described with reference to FIGS. 1A and 1B. The video system ofthis VTR includes a video clock converter 11 and video clock converter12, which work together to convert the data rate by multiplying it by afield frequency ratio as in the 50-fields/sec VTR. In this case, thedata rate conversion is made between 74.25 MHz and 59.4 MHz(=74.25MHz×48/60).

The data rate conversion is shown in FIGS. 10A, 10B and 10C. FIG. 10Ashows a frame of 60 Hz in field frequency, FIG. 10B shows a frame of 48Hz in field frequency, and FIG. 10C shows a frame (signal form) resultedfrom processing of the 48-Hz frame by the video clock converter 11. Aswill be seen from FIGS. 10A, 10B and 10C, the effective area will remainunchanged even after the conversion by the input video clock converter11 and output video clock converter 12 as in the aforementioned50-fields/sec VTR, only the ineffective area (blanking area) is changed,and thus the frame including the ineffective and effective areas isquite the same as that in the 60-fields/sec VTR after the conversion.

On the other hand, audio data is to be processed to have a total numberof bits per field, which is the same as that in the 60-fields/sec VTRwhich is the base of this 48-fields/sec VTR. However, the fieldfrequency of 48 fields/sec provides no convenient number of samples perfield and number of bits per sample. In the 60-fields/sec VTR being thebase for the 48-fields/sec VTR, audio data can be recorded in the formatof 800 samples/field×24 bits/sample. Taking this fact in consideration,audio input has to be processed in the 48-fields/sec VTR to have a fieldfrequency of 48 kHz. The 48 fields/sec leads to 1000 samples/field. Theformat of 800 samples/field×24 bits/sample can simply be converted to19200 bits per field. The latter is also 1000 samples/field×19.2bits/sample. However, since the number of 19.2 bits per sample is notany integral number, so a complete completion cannot be attained. For asolution to this problem, a format of 960 samples/field×20 bits/sample,which approximate to the format of 1000 samples/field×19.2 bits/sample,is first converted to the format of 800 samples/field×24 bits/sample.That is, as shown in FIG. 9A, the format of 1000 samples/field×20bits/sample (48 kHz and 48 fields) is once converted by an audio rateconverter 13 into a format of 960 samples/field×20 bits/sample(=46.08kHz and 48 fields/sec). Then, the signal thus obtained is converted bythe audio data packing unit 9 into a format of 800 samples/field×24bits/sample (36.864 kHz=46.08 kHz×48/60 and 48 fields/sec). Theresultant signal is encoded at the field frequency-ratio rate as in the50-fields/sec VTR.

The decoding is an inversion of the encoding. The audio data depackingunit 10 converts the format of 800 samples/field×24 bits/sample (36.864and 48 fields/sec) into a format of 960 samples/field×20 bits/sample(46.08 kHz and 48 fields), and then an audio rate converter 14 convertsthe latter format into a format of 1000 samples/field×20 bits/sample (48kHz and 48 fields/sec) which is a VTR output. At this time, the samplingrate is converted into a 46.08 kHz. However, since the sound rangeaudible to the human ears is generally 20 kHz, so the sampling frequencymay be a one above 40 kHz even when the sampling theorem is applied andthus the sampling frequency of 46.08 kHz is sufficient even when theperformances of the D-A converter, A-D converter, etc. are taken inconsideration. Thus, even when there is not available any integral totalnumber of bits per field in case it is simply assumed that the totalnumber of bits per sample in a VTR should be the same as that in a basicVTR, a sampling rate converter can be used to assure an integral totalnumber of bits per sample without lowering the sampling frequency somuch.

In the 48-fields/sec VTR, the data format may be converted into 800samples/field×24 bits/sample by adding a 200-bit stuffing (meaninglessdata to the format of 1000 samples/field×19 bits/sample without usingthe sampling rate converter as above. In this case, however, since theaudio data packing/depacking sequence will be long, a large-size FIFO isrequired. Namely, the least common multiple in the relation between 19bits and 24 bits is higher than that in the relation between 20 bits and24 bits, and the FIFO should accordingly be larger in size.

In the foregoing, the present invention has been described concerningthe embodiments thereof in compliance with the “Hi-Vision” standard.According to the “Hi-Vision” standard, data different in field frequencyfrom one another are the same in effective area as having been describedwith reference to FIGS. 6A, 6B and 6C and FIGS. 10A, 10B and 10C, andthus the data are not subjected to any line-conversion filtering by thevideo clock converters 11 and 12 in FIGS. 5A and 5B. According to theSTANDARD standard (SD), however, the frame of a effective area for the60-fields/sec VTR includes 720 samples×480 lines while that of a validfor the 50-fields/sec VTR includes 720 samples×576 lines. Namely, theseVTRs are different in number of scanning lines from each other and hencethe data have to undergo a line-conversion filtering. FIGS. 11A and 11Bare block diagrams showing together a basic 60-fields/sec VTR accordingto the STANDARD standard. FIG. 11A shows the recorder section of the VTRand FIG. 11B shows the player section of the VTR. The audio basebandprocessors 3 and 8 are the same as in the example shown in FIGS. 1A and1B. This VTR further includes an input baseband processor 15, videocompressor 16, ECC encoder and audio/video coupler 17, ECC decoder andaudio/video separator 18, video expander 19 and an output video basebandprocessor 20, which form together an SD data processing block.

FIGS. 12A and 12B are block diagrams showing together a 50-fields/secVTR designed to accommodate data originated from the 60-fields/sec SDVTR. FIG. 12A shows the recorder section of the VTR and FIG. 12B showsthe player section. Also, FIGS. 13A, 13B and 13C show differences amongframes of different field frequencies and frames after processed for thefield frequency of 50 fields/sec. FIG. 13A shows a frame whose fieldfrequency is 60 Hz, FIG. 13B shows a frame whose field frequency is 50Hz, and FIG. 13C shows a frame (signal form) resulted from processing ofthe 50-Hz frame by the video clock converter. As shown in FIGS. 12A and12B, the video baseband processes 21 and 24 make input and outputbaseband processing operations, respectively, which are quite differentfrom those made by the video baseband processors 15 and 20 in FIGS. 11Aand 11B, respectively, for signals of 60 fields/sec in field frequencybecause the video baseband processes 21 and 24 are for signals of 50fields/sec in field frequency and different in number of lines. A videoline and clock converter 22 in FIG. 12A corresponds to the video clockconverter 11 in FIG. 5A and provides a line conversion filtering toconvert the effective frame of 720 samples×576 lines in the50-fields/sec VTR into an effective frame of 720 samples×480 lines inthe basic 60-fields/sec VTR. As shown in FIGS. 13A, 13B and 13C, thevideo line and clock converter 22 converts the frame and also changesthe clock.

A video line and clock converter 23 in FIG. 12B corresponds to the videoclock converter 12 in FIG. 5B, and makes a line conversion filtering toconvert the effective frame of 720 samples×480 lines in the basic60-fields/sec VTR into an effective frame of 720 samples×576 lines inthe 50-fields/sec VTR, thereby restoring the original number of lines.As shown in FIGS. 13B and 13C, the video line and clock converter 23converts the frame and also changes the clock. As in the Hi-Visionsystem, the ECC encoder and audio/video coupler 17, video compressor 16,ECC encoder and audio/video separator 18 and video expander 19 work at adifferent rate and thus the circuit may be the same as in the basic60-fields/sec VTR. Also, audio signals can be processed as in theHi-Vision system, and thus the audio data packing unit 9, audio datadepacking unit 10, audio baseband processor 3 and audio basebandprocessor 8 are quite the same as those n the Hi-Vision system VTR shownin FIGS. 5A and 5B. The above explanation concerns a VTR for SD data.According to the present invention, even data having a frame format notcompatible with a VTR for data having a field frequency can be recordedand played by the VTR by designing the VTR to be able to subject thedata to the filtering for frame format conversion.

Next, a developed form of the VTR shown in FIGS. 5A and 5B will bedescribed. The audio data depacking unit 10 in the 50-fields/sec VTRshown in FIGS. 5A and 5B is built in the ECC encoder and audio/videoseparator 5, which is shown in the form of a block diagram in FIGS. 14Aand 14B. FIG. 14A shows the recorder section of the VTR and FIG. 14Bshows the player section. That is, the VTR shown in FIGS. 14A and 14Bcan support both data of 60 and 50 fields/sec in field frequency. Theonly difference between the VTRs in FIGS. 14A and 14B is the ratiobetween the field frequencies (50/60). For example, the output from thevideo compressor 2 is 38.6666 MHz=46.4 MHz×50/60.

The ECC encoder and audio/video coupler 4′ is shown in detail in FIG.15. In this circuit, video data having undergone C2 ECC processing by avideo C2 ECC processor 35 is sent to an SD RAM read/write control unit31. On the other hand, audio data is converted from serial to parallelby a S-P converter 25, and sent to a controller 26. The controller 26provides RateConv RAM write control (for control over data write to aRateConv RAM 28) and ECC start control (for control over start of aprocessing by another controller 29). The controller 26 includes aconvert register 34, which will be described in detail later. TheRateConv RAM (will be referred to as “RC RAM” hereunder) 28 is adual-port RAM in which clock is switched from the audio 48-kHz systemclock to an internal system clock (66 MHz). The controller 29 controlsread from the RC RAM 28, C2 RAM 30, adds C2 ECC parity to data andgenerates a write address in an SD RAM. The SD RAM read/write controlunit 31 controls access to an SD RAM 32. There is provided a C1 ECCprocessor 33 to generate a read address in the SD RAM 32, appends the C1ECC parity to data, puts the data on an RF clock and provides RF data.There is also provided an audio timing generator 27 to receive a fieldsignal and sampling period (FS) signal and counts them in one field. Inthis case, since the sampling frequency is 48 kHz in both the data of 60and 50 fields/sec in field frequency, so 800 samples are counted perfield by a counter in the case of 60-fields/sec data to provide aprocessing timing to the controller 26 and C1 ECC processor 31, while960 samples are counted per field in the case of 50-fields/sec data toprovide a processing timing to the controller 26 and C1 ECC processor33.

FIG. 16 is an audio timing chart of the ECC encoder and audio/videocoupler 4′, showing the processing of data having a field frequency of60 fields/sec and including 24 bits per sample. Namely, the timing ofprocessing after 20 bits/sample is converted into 24 bits/sample isshown for the field frequency of 50 fields/sec. First, the audioprocessing timing for the basic field frequency of 60 fields/sec will bedescribed. The RC RAM 28 consists of three banks each capable of storing48 samples×24 bits/sample of data. The figures “0”, “1” and “2” in FIG.16 are numbers for the RC RAM banks. As seen from FIG. 16, 800samples/field=48 samples/bank×16 banks+32 samples(=1 bank). Audio datais written at an FS (with sampling frequency of 48 kHz) rate to the RCRAM 28. Fld-Start (Field-Start) and C2-Start are processing timingcontrol signals supplied from the controller 26. When the Fld-Start isreceived, new field data are written to the RC RAM 28. As shown in FIG.16, the new field data are sequentially written to the RC RAM 28 firstinto the bank 2 and then the bank 0. When the C2-Start is received, theC2 ECC processing of the banks 2 and 0 starts. With a system clock of 66MHz, data are read from the RC RAM 28 in the direction of C2. The C2 ECCprocessing is controlled by the controller 29, a C2 parity is added tothe data and the data is written to the C2 RAM 30 in the direction ofC2. Upon write of all the data to the C2 RAM 30, data are read from theC2 RAM 30 in the direction of C1, sent along with an SD RAM writeaddress to an SD RAM read/write control unit 31 and written to an SD RAM32. The processing is done in a time-sharing manner from a channel 0 to7. The C2-Start is supplied each time data for two banks are written tothe RC RAM 28. At the end of a field, the C2-Start is supplied alongwith the Fld-Start to process data remaining in the current field. Atthe field end, data for 32 samples, smaller than data for one bank, areprocessed. The Fld-Start and C2-Start are generated by the controller 26from a control signal supplied from the audio timing generator 27. Dataof 60 fields/sec in field frequency thus undergo the audio ECC encoding.The convert register 34 is not used for any data having the basic fieldfrequency of 60 fields/sec.

Next, signals having a field frequency of 50 fields/sec, supplied tothis VTR, will be described. As shown in FIG. 14A, audio data suppliedto the ECC encoder and audio/video coupler 4′ and having the fieldfrequency of 50 fields/sec has a format of 960 samples/field×20bits/sample (48 kHz). This data is to be converted into a format of 800samples/field×24 bits/sample by audio data packing. For this audio datapacking, the convert register 34 shown in FIG. 15 is used. The S-P(serial-parallel) converter 25 in FIG. 15 processes data having a formatof 960 samples/fields×20 bits/sample similarly to the data having thefield frequency of 60 fields/sec to convert the data from serial toparallel. The parallel data is supplied from the S-P converter 25 to thecontroller 26 with LSB first and in units of 8 bits. For sending data ata rate of 20 bits/sample, the 20 bits. are divided into four LSBs (leastsignificant bits), eight MDBs (middle bits) and eight MSBs (mostsignificant bits), and the data is converted by the converter register34 into a 24-bit data. The unit of sequence is 960 samples/field×20bits/sample. Six samples are taken as one sequence. This sequence isconverted into 24 bits/sample×5 samples. That is, six samples/field×20bits/sample is converted into five samples×24 bits/sample. Therefore,960 samples/field×20 bits/sample is converted into 800 samples/field×24bits/sample.

The operation of the convert register 34 will be described herebelowwith reference to FIG. 17. The convert register 34 includes 24 registers(for 24 bits). Input data is of 20 bits per sample. As shown in FIG. 17,audio data is written to the register with the control signalField-Start being as the top of a conversion sequence, with LSB firstand densely at the MSB side. As mentioned above, one sample of data isreceived as four LSBs, eight MDBs and eight MSBs and thus it is writtenin these three parts to the register. When the data has been writtendown to the MSB of the register, it is cyclically written at the LSBagain. In FIG. 17, bits being written are shown at the left side andbits being read are shown at the right side. As far as the fourthexample in FIG. 17 is concerned for example, data is written to onlyfour MSBs while data is read from eight LSBs. It should be noted thatwhen data write to and read from the convert register conflict with eachother, the write is preferentially done.

Data is not read from the convert register 34 for the first one sample(pause), and then data is read in units of 8 bits starting with the LSB.The data are to be written to the RC RAM. “A” to “F” in FIG. 17 indicateindependent samples, respectively, showing how data are to be packed inthe audio data packing. Data is read from the convert register 34 with a48-kHz clock. In this case, a pause is taken at the leading sample ofone sequence. No data is written to the RC RAM 28 during pause inreading the convert register 34. That is, write to the convert register34 and read from the RC RAM 28 will not be made at every six samples.Also, there is provided an internal counter to generate a C2 ECCprocessing start control signal, Fld-Start signal and C2-Start signal,which are to be supplied to the controller 29. In the 48-kHz system, theinternal counter is so operated as to take pause at every six samples togenerate the above signals. The operation of the internal counter for 95samples (in the 48-kHz system) in 60-fields/sec VTR corresponds to thatfor 114 samples (in the 48-kHz system) (=95×6/5) in the 50-fields/secVTR. In the 60-fields/sec VTR, a C2-Start signal next to thesuperposition of the Fld-Start and C2-Start signals in FIG. 16 appearsat every 96 samples (48-kHz system). In the 50-fields/sec VTR, thecounter advances by 95 samples (60 fields/sec) when it has counted 114samples, takes pause because a next sample comes at the sequence top,and advances by 96 samples (60 fields/sec) when it counts a next sample.That is, the C2-Start signal next to the Fld-Start signal will appear atthe 116th sample (114+1+1). Thus, the C2 ECC processing is made by thecontroller 29 at a rate multiplied by the field frequency ratio. It isimportant at this time that the circuit provided downstream of the RCRAM 28 and controller 29 operates at the rate multiplied by the fieldfrequency ratio because of the RAM write control and processing startcontrol and they need not any circuit modification as in the60-fields/sec VTR. Also, the rate conversion is made by multiplying arate by the field frequency ratio by causing the internal counting andcontrol not to be done at every six samples during the audio datapacking conversion. Compared with the method in which the audio datapacking is done with two clocks of 48 kHz and 40 kHz as shown in FIG.7A, the rate conversion can be made with only one clock of 48 kHz and byonly the 24 registers in the convert register 34.

Next, the internal block construction of the ECC decoder and audio/videoseparator 5′ in the player section will be illustrated and describedwith reference to FIG. 18. In a C1 ECC decoder 36, RF data undergoes C1ECC decoding (error correction) and the data thus decoded is written tothe SD RAM 32 via the SD RAM read/write control unit 31. The video C2ECC decoder 42 makes C2 ECC decoding of the video data read by the SDRAM read/write controller 31 from the SD RAM 32 and outputs the data. Onthe other hand, concerning the audio data, a timing generator (TG) 38included in the separator 5′ is supplied with a field signal andsampling frequency (FS) signal to count one field of data for the audiodata. In this case, since the sampling frequency is 48 kHz for both the60- and 50-fields/sec VTRs, so the counter counts 800 samples per fieldin the 60-fields/sec VTR to give a timing of operation to a controller39 and C1 ECC decoder 36. In the 50-fields/sec VTR, the counter counts960 samples per field to give an operation timing to the controller 39and C1 ECC decoder 36. The controller 39 generates a C2 ECC decodingtiming and sends it to another controller 37. Also, the controller 39controls read from the RC RAM 28. The controller 39 incorporates aconvert register 41 which will be described in detail later. Thecontroller 37 makes C2 ECC decoding according to the C2 ECC decodingstart timing signals Fld-Start and C2-Start supplied from the controller39. The controller 37 reads necessary audio data in the direction of C1from the SD RAM 32 through the SD RAM read/write control unit 31, andwrites it to the C2 RAM 30 in the direction of C1. When the audio datahave been cumulated in the C2 RAM 30, the controller 37 will read audiodata in the direction of C2 for C2 ECC decoding, and write the audiodata having thus undergone the C2 ECC decoding to the RC RAM 28. Theoperation of the controller 37 and data write to the C2 RAM 30 and RCRAM 28 are done under the control of an internal system clock of 66 MHz.The controller 39 reads audio data from the RC RAM 28 with a clock of 48kHz. The audio data thus read is sent to an S-P (serial-parallel)converter 40. The S-P converter 40 conceals and mutes the audio data,and then converts the audio data thus processed from parallel to serial.The audio data thus processed is delivered as audio output from the ECCencoder and audio/video separator 5′.

FIG. 19 is an audio timing chart of the ECC decoder and audio/videoseparator 5′, showing the processing of data having a field frequency of60 fields/sec and including 24 bits per sample. Namely, the timing ofprocessing before 24 bits/sample is converted into 20 bits/sample isshown for the field frequency of 50 fields/sec. First, the audioprocessing timing for the basic field frequency of 60 fields/sec will bedescribed. The RC RAM 28 consists of three banks each capable of storing48 samples×24 bits/sample of data. The figures “0”, “1” and “2” in FIG.19 are numbers for the RC RAM banks. As seen from FIG. 19, 800samples/field=48 samples/bank×16 banks+32 samples (=1 bank). Fld-Start(Field-Start) and C2-Start are processing timing control signalssupplied from the controller 39. When the Fld-Start is received, newfield data are read from the RC RAM 28. As shown in FIG. 19, the newfield data are sequentially read from the banks 2 and 0 of the RC RAM28. Then, data are continuously read from the RC RAM 28 at the FS rate.As shown in FIG. 19, data are read cyclically from the banks of the RCRAM 28. The C2-Start signal is basically provided each time data is readfrom two banks of the RC RAM 28. Since near field data has to be readfrom the RC RAM 28 once the Fld-Start signal is provided, so new fielddata read from the first bank is subjected to C2 ECC decoding when aC2-Start signal is received before the Fld-Start signal. In FIG. 19, thebank 2 is the first bank for the new field data and the data undergoesthe C2 ECC decoding. In the first processing of the new field data, datafor one bank of the RC RAM 28 is first subject to the C2 ECC decoding.When the Fld-Start signal is received, data for the next two banks areprocessed, and then each time the C2-Start signal is received, data forthe two banks are processed. The audio ECC decoding is thus done in the60-fields/sec VTR. The basic 60-fields/sec VTR does not use the convertregister 41.

Next, signals having a field frequency of 50 fields/sec, supplied tothis VTR, will be described. As shown in FIG. 14B, audio data suppliedto the ECC decoder and audio/video separator 5′ and having the fieldfrequency of 50 fields/sec has a format of 960 samples/field×20bits/sample (48 kHz). The 800 samples/field×24 bits/sample of data is tobe converted into a format of 960 samples/field×20 bits/sample by audiodata depacking. For this audio data depacking, the convert register 41shown in FIG. 18 is used. Data read from the RC RAM 28 in FIG. 18 is of24 bits/sample and has a format of 800 samples/field×24 bits/sample.This data is converted by the convert register 41 into 960samples/field×20 bits/sample by the audio data depacking. For sendingdata to the S-P converter 40 at a rate of 20 bits/sample, the controller39 in FIG. 18 divides the data into four LSBs, eight MDBs and eight MSBsas in the encoding process. The unit of conversion sequence is 960samples/field×20 bits/sample and six samples are taken as one sequenceas in the encoding process. That is, five samples/field×24 bits/sampleis converted into six samples×20 bits/sample. Therefore, 800samples/field×24 bits/sample will be converted into 960 samples/field×20bits/sample.

The operation of the convert register 41 will be described herebelowwith reference to FIGS. 20A and 20B. The convert register 41 includes 24registers (for 24 bits). Input data is of 24 bits per sample. As shownin FIGS. 20A and 20B, audio data is written to the register with thecontrol signal Field-Start being as the top of a conversion sequence. Atthis time, for forward playing shown in FIG. 20A, the data is writtenwith LSB first and densely at the MSB side. For reverse playing shown inFIG. 20B, the data is written with MSB first and densely at the LSBside. Also for the forward playing for data read, data is read with LSBfirst in the direction of MSB. For the reverse playing, the data is readwith MSB first in the direction of LSB. For providing data from thecontroller 39 to the S-P converter 40, the data is divided into fourLSBs, eight MDBs and eight MSBs correspondingly to the LSB first or MSBfirst mode in the reading from the convert register. Therefore, forforward playing, the data is read with LSB first, while for reverseplaying, the data is read with MSB first. For data decoding, data iscyclically written to and/or read from the convert register 41 as in theencoding operation. It should be noted that when data write to and readfrom the convert register 41 conflict with each other, the read ispreferentially done.

Data write to the convert register is controlled so that after fivesamples are written to the convert register, no data is data for onesample. That is, no read from the RC RAM 28, namely, no write to theconvert register 41, will be made at every six samples. Also, there isprovided an internal counter which generates a C2 ECC processing startcontrol signal, Fld-Start signal and C2-Start signal, which are to besupplied to the controller 37. In the 48-kHz system, the internalcounter is so operated as to take pause at every six samples to generatethe above signals. The operation of the internal counter for 95 samples(in the 48-kHz system) in 60-fields/sec VTR corresponds to that for 114samples (in the 48-kHz system) (=95×6/5) in the 50-fields/sec VTR. Inthe 60-fields/sec VTR, a C2-Start signal next to the superposition ofthe Fld-Start and C2-Start signals in FIG. 19 appears at every 96samples (48-kHz system). In the 50-fields/sec VTR, the counter advancesby 95 samples (60 fields/sec) when it has counted 114 samples, andadvances by 96 samples (60 fields/sec) when it counts a next sample.That is, the C2-Start signal next to the Fld-Start signal will appear atthe 115th sample (114+1). Thus, the C2 ECC decoding is made by thecontroller 37 at a rate multiplied by the field frequency ratio. It isimportant at this time that the circuit provided downstream of the RCRAM 28 and controller 37 operates at a rate multiplied by the fieldfrequency ratio because of the RAM read control and processing startcontrol and they need not any circuit modification as in the60-fields/sec VTR. Also, the rate conversion is made at a ratemultiplied by the field frequency ratio with the controller 39 causednot to do the internal counting and control at every six samples duringthe audio data depacking conversion. Compared with the method in whichthe audio data depacking is done with two clocks of 48 kHz and 40 kHz asshown in FIG. 8A, the rate conversion can be made with only one clock of48 kHz and by only the 24 registers in the convert register 34.

The shuttle play will be considered herebelow. In the shuttle play,various fields of data will be mixed. In the normal play, the ECC blocksshown in FIG. 4B are all in the same field, so that the C2 ECC can beapplied to the data. In the shuttle play, however, the sync data(C1-directional data) remain unchanged but sync data in different fieldsare mixed in the direction of C2, so that the C2 ECC decoding cannot beapplied to the data in the shuttle play. Thus, when the audio data isdepacked in the shuttle play, the audio data depacking sequence is keptas shown in FIG. 21 but depacked data are in different-fields. It shouldbe noted that the sample data packed in 24 bits by the audio datapacking remains unchanged without the bit data in the data pack not indifferent fields. “A0”, “B0”, “B1”, “C1”, “C2”, “D2”, “D3”, “E3”, “E4”and “F4” in FIG. 21 are independent sample data. “A” to “F” indicate thenumbers for data in the data depacking sequence, and numbers next tothese alphabets indicate fields, respectively. Namely, the data areshown depacked in independent field data. As will be seen from FIG. 21,“A0” and “F4” are contained, without any missing, in the first and lastdata packs, respectively, in five samples (24 bits/sample after packed)in the audio data depacking sequence. That is, it will be seen thatthese “A0” and “F4” can be restored to their initial forms of 20bits/sample without any missing even when they are subjected to theaudio data depacking. Other than “A0” and “F0” will be concealed aserror data by the S-P converter 40 in FIG. 18 because they are indifferent fields. More specifically, invalid data are interpolated withvalid data to provide an output. FIG. 21 shows how the audio data ischanged in the above series of operations.

As an application of the above method, any data may be used whose 16MSBs have been restored to their initial state while all its 20 bits arenot restored to the original data without any missing. This will bedescribed with reference to FIG. 22. Of the 20-bit sample data alreadysubjected to the audio data packing, the four LSBs are replaced withzeros to make the 16 MSBs valid. Thus, the “A0”, “B1” and “F4” are madevalid as shown in FIG. 22. Other than these playable data are concealedas error data as above. In this case, the four LSBs in the “A0” and “F4”whose 20 bits are all playable are replaced with zeros, which isintended for a simple processing. Since all the 20 bits can be played atthe start and end of the audio data depacking sequence, so the 20 bitsmay be used as playable data with the four LSBs not replaced with zerosin these samples.

INDUSTRIAL APPLICABILITY

According to the present invention, it is possible to implement, basedon an audio recording/playing apparatus for audio data of a certainfield frequency, an audio recording/playing apparatus which canaccommodate data of all kinds of field frequencies and audio samplingfrequencies without changing the data format. Also, since almost all theoperations such as audio baseband processing etc. are the same as in thebasic recording/playing apparatus except for the rate which is to bechanged, so almost all the circuits of the basic apparatus can be usedfor the derived recording/playing apparatus. Further, when it isintended to implement an audio recording/playing apparatus compatiblewith audio data of all the kinds of field frequencies, since almost allthe circuits of the basic apparatus can be used with the different fieldfrequencies, so an audio recording/playing apparatus compatible withdata of such many field frequencies can be implemented easily.

According to the present invention, the format of audio data can easilybe converted by the ECC encoding circuit without having to provide anydedicated device (FIFO) for the audio data format conversion. Also,since it is not necessary to provide the ECC encoding circuit with anyclock dedicated for the audio data format conversion, so it suffices tosupply a single kind of baseband audio clock to the ECC encodingcircuit. Provision of only 24 registers (24 bits) in the ECC encodingcircuit permits to implement the data format conversion. Also, just bymodifying a part of the control of the ECC encoding circuit, the lattercan be made usable as it is for almost all the processing operationsafter the audio data format conversion (such as the rate convert RAMprocessing, C2 ECC encoding, etc.), so that little additional circuit isrequired for such operations.

According to the present invention, the format of audio data can easilybe converted by the player-side ECC decoding circuit similarly to therecorder-side ECC encoding circuit without having to provide anydedicated device (FIFO) for the audio data format conversion. Also,since it is not necessary to provide the ECC decoding circuit with anyclock dedicated for the audio data format conversion, so it suffices tosupply a single kind of baseband audio clock to the ECC decodingcircuit. Provision of only 24 registers (24 bits) in the ECC decodingcircuit permits to implement the data format conversion. Also, just bymodifying a part of the control of the ECC decoding circuit, the lattercan be made usable as it is for almost all the processing operationsbefore the audio data format conversion (such as the rate convert RAMprocessing, C2 ECC decoding, etc.), so that little additional circuit isrequired for such operations. Also, the recording/playing apparatus thusderived from the basic apparatus can made trick plays such as formatvariable play and reverse variable play.

The recording/playing apparatus according to the present invention isintended for playing a medium having recorded therein audio data whoseformat has been converted. In the shuttle play, packed data of differentfields are also reproduced. In this case, restoration of the data asthey by the reverse format conversion will result in data in which MSBsand LSBs of sample data in quite different fields are synthesized by thereverse format conversion. Therefore, the data will have quite differentvalue from that in the recorded data, and thus the shuttle play soundwill be a large noise. To avoid this, all packed audio data areunavoidably muted for shuttle play thereof For shuttle play of thepacked audio data in which audio data in different fields are mixed, theshuttle play sound can be produced by providing only valid ones,including a correct bit string, of the sample restored to the specificformat by the converter.

According to the present invention, it is possible to implement, basedon a video recording/playing apparatus for video data of a certain fieldfrequency, a video recording/playing apparatus which can accommodatedata of all kinds of field frequencies and video frames without changingthe data format. Also, since almost all the operations such as videobaseband processing, video compression, expansion, error-correctivecoding, etc. are the same as in the basic recording/playing apparatusexcept for the rate which is to be changed, so almost all the circuitsof the basic apparatus can be used for the derived recording/playingapparatus. Further, when it is intended to implement a videorecording/playing apparatus compatible with video data of all the kindsof field frequencies, since almost all the circuits of the basicapparatus can be used with the different field frequencies, so a videorecording/playing apparatus compatible with data of such many fieldfrequencies can be implemented easily. In addition, in case the videoeffective frame in the derived apparatus is the same as in the basicapparatus, all the recording media will have the same formatindependently of the field frequency. Therefore, even by playing amedium having data recorded therein with a certain field frequency witha different field frequency, a picture can be reproduced.

1. A digital audio recording apparatus, comprising: an input unit for accepting input audio data having a specific sampling frequency, a specific field frequency, and a specific format and for performing baseband processing of the input audio data; a processor designed to process audio data having a basic field frequency and a basic format and to perform error-corrective encoding; an output unit for writing audio data output from the processor to a recording medium; and a converter provided between the input unit and the processor to convert the first audio data to the second audio data, wherein, when the specific field frequency is different from the basic field frequency and the specific format is different from the basic format, the converter converts the specific sampling frequency at a ratio between the specific field frequency and basic field frequency and converts the specific format to the basic format before passing the input audio data to the processor; wherein the processor operates with a clock corresponding to the converted sampling frequency to perform error-corrective encoding of the audio data of the basic format, wherein the converter converts the specific format to the basic format by jointly changing the number of samples per field and number of bits per sample while maintaining the total number of bits per field, wherein the total number of bits per field is calculated as the product of the number of samples per field and number of bits per sample, and wherein the converter converts the specific sampling frequency by changing the number of samples per field.
 2. The apparatus as set forth in claim 1, wherein when the total number of bits per field varies between the specific format and the basic format, the converter corrects the number of samples per field by converting the specific sampling frequency of the input audio data, and adjusts the corrected total number of bits per field to the total number of bits per field.
 3. The apparatus as set forth in claim 1, wherein when the total number of bits per field varies between the specific format and the basic format, the converter corrects the total number of bits by adding dummy data corresponding to deficit bits to the specific format and adjusts the total number of specific-formatted bits to that of basic-formatted bits.
 4. The apparatus as set forth in claim 1, wherein the converter converts the specific format to the basic format by writing audio data consisting of a bit stream of serially arranged samples to FIFO in units of a number of specific-formatted bits, reading the audio data in units of a number of basic-formatted bits, and jointly changing the number of samples per field and number of bits per samples.
 5. The apparatus as set forth in claim 4, wherein the converter converts the specific format to the basic format by controlling the write and read of the audio data to and from the FIFO synchronously with the specific field frequency.
 6. A digital audio playing apparatus comprising: an input unit for reading, from a recording medium, audio data having a basic sampling frequency, a basic field frequency, and a basic format; a processor designed to process the audio data and to operate with a clock corresponding to the basic sampling frequency to decode the audio data for at least error correction of the audio data; an output unit for performing baseband processing of the audio data output from the processor and for supplying the audio data to a playback device; and a converter provided between the processor and the output unit for converting the audio data according to a specific sampling frequency, a specific field frequency, and a specific format, wherein the processor operates with the clock corresponding to the basic sampling frequency of the read audio data to perform error-corrective decoding and expand the audio data, wherein when the specific field frequency is different from the basic field frequency and the specific format is different from the basic format, the converter restores the audio data to the specific format and converts the basic sampling frequency of the read audio data into the specific sampling frequency at a ratio between the specific field frequency and basic field frequency before passing the audio data to the output unit, wherein the converter restores the audio data from the basic format to the specific format by jointly changing the number of samples per field and number of bits per sample while maintaining the total number of bits per field, wherein the total number of bits per field is calculated as the product of the number of samples per field and number of bits per sample, and wherein the converter converts the basic sampling frequency by changing the number of samples per field.
 7. The apparatus as set forth in claim 6, wherein when the total number of bits per field varies between the specific format and the basic format, the converter corrects the number of samples per field by converting the basic sampling frequency of the audio data once restored from the basic format to the specific format, and converts the audio data into the specific format.
 8. The apparatus as set forth in claim 6, wherein when the total number of bits per field varies from the specific format to the basic format, the converter restores the audio data to the specific format by adding excess dummy data to the audio data, and converts the audio data into the specific format by removing the dummy data from the audio data.
 9. The apparatus as set forth in claim 6, wherein the converter restores the basic format to the specific format by writing audio data consisting of a bit stream of serially arranged samples to FIFO in units of the number of basic-formatted bits, reading the audio data in units of the number of specific-formatted bits, and changing the number of samples per field and number of bits per samples in combination.
 10. The apparatus as set forth in claim 9, wherein the converter restores the basic format to the specific format by controlling the write and read of the audio data to and from the FIFO synchronously with the specific field frequency.
 11. A digital audio playing apparatus comprising: an input unit for reading, from a recording medium, audio data having a basic sampling frequency, a basic field frequency, and a basic format; a processor for processing the audio data and to operate with a clock corresponding to the basic sampling frequency to decode the audio data for at least error correction of the audio data; an output unit for performing at least baseband processing of the audio data output from the processor and for supplying the audio data to a playback device; a shuttle play control unit; and a converter provided between the processor and the output unit for converting the audio data according to a specific sampling frequency, a specific field frequency, and a specific format, wherein the processor operates with the clock corresponding to the basic sampling frequency of the read audio data to perform error-corrective decoding and expand the audio data, wherein when the specific field frequency is different from the basic field frequency and the specific format is different from the basic format, the converter restores the audio data to the specific format, converts the basic sampling frequency of the read audio data into the specific sampling frequency at a ratio between the specific field frequency and basic field frequency before passing the audio data to the output unit, and wherein the converter restores the audio data from the basic format to the specific format by jointly changing the number of samples per field and number of bits per sample while maintaining the total number of bits per field, wherein the total number of bits per field is calculated as the product of the number of samples per field and number of bits per sample; and wherein, during shuttle play of audio data of different fields, the shuttle play control unit passes, to the output unit, only valid samples having a correct bit string, of the samples restored by the converter to the specific format.
 12. The apparatus as set forth in claim 11, wherein the shuttle play control unit passes, to the output unit, substitute samples obtained by interpolating the valid samples instead of invalid samples having no correct bit string, of the samples restored to the specific format.
 13. The apparatus as set forth in claim 11, wherein the shuttle play control unit substitutes zero for an incorrect bit string in at least a part of an invalid samples having correct and incorrect bit strings, among the samples restored to the specific format, and converts the invalid sample into a valid sample. 